The present invention concerns a device for fastening hammers in axially extending recesses of rebound-mill rotors with a form-locked connection between each hammer and one side of the corresponding recess and a force-locked connection on the other side by means of at least one wedge-shaped clamping strip which is acted on in the direction of clamping by a plurality of pressing elements each of which has a clamping piston acted on by a pressure medium, they being connected to each other by a common pressure line which can be closed by a valve.
A device of the type described above for the fastening of hammers in rebound-mill rotors is already known. The clamping pistons which are provided instead of mechanical clamping elements are arranged in the bottom of the axially extending recesses in the rebound-mill rotor and connected to each other by a common pressure conduit which is developed in the rotor and is filled with a hydraulic fluid. After the insertion of the hammers and clamping ledges the pressure conduit is filled with hydraulic fluid. As a result, the piston rods of the clamping pistons travel upward and displace the clamping ledge. By the application of a predetermined excess pressure in the hydraulic fluid assurance is to be provided that a sufficient additional clamping action is always available.
The known device has the disadvantage that as the result of the use of a non-compressible hydraulic fluid as pressure medium, the pressure which has built up in the hydraulic system suddenly collapses upon the occurrence of slight leakage losses or upon a jigging of the hammers or clamping ledges so that the clamping pistons which act on the clamping ledge cannot by themselves assure a dependable attachment of the hammers. In practice therefore, in the case of the known devices, retensioning springs for the clamping pistons are provided and a mechanical fixing of the clamping ledge present in the clamping position by means of nuts or bolts is effected. In this way, the known device is not only structurally expensive but it is also cumbersome to handle, since after the clamping position is reached each clamping ledge must be individually secured by the hydraulic system.
The object of the present invention is so to improve a device of the afore mentioned type that, while retaining the clamping pistons, the use of retensioning springs and in particular of mechanical locking elements can be dispensed with and a particularlly simple construction created which avoids expensive and weakening machining of the rebound-mill rotor.